Cylinders of an engine may be selectively activated and deactivated to reduce engine fuel consumption and match engine torque production to engine torque demand. For example, fuel consumption of an internal combustion engine may be reduced via reducing an actual total number of cylinders of the engine combusting air and fuel. The engine's reduced displacement may reduce engine pumping losses and increase efficiency of active cylinders that combust air and fuel. However, deactivating a cylinder longer than desired may increase engine emissions. Therefore, it may be desirable to provide a way of deactivating engine cylinders to increase engine fuel economy that does not significantly increase engine emissions.
The inventors herein have recognized the above-mentioned disadvantages and have developed an engine system, comprising: an engine including a first cylinder with a first intake valve and a first exhaust valve; a first deactivating valve operator in mechanical communication with the first intake valve; a first non-deactivating valve operator in mechanical communication with the first exhaust valve; and a controller including instructions to activate the first intake valve in response to an estimate of an oil amount in a cylinder.
By reactivating a cylinder in response to an estimate of oil in the deactivated cylinder, it may be possible to provide the technical result of decreasing engine fuel consumption while not increasing engine emissions. For example, cylinders of an engine that have been deactivated may be reactivated when an estimate of oil in the deactivated cylinder exceeds a threshold amount. Other active engine cylinders may be deactivated so that the total actual number of deactivated engine cylinders (e.g., cylinders not combusting air and fuel and cylinders with intake and exhaust valves held closed over an entire engine cycle) may remain constant from engine cycle to engine cycle when driver demand torque is constant. In this way, pressure in engine cylinders may be elevated to reduce engine oil consumption.
The present description may provide several advantages. For example, the approach may reduce vehicle emissions. In addition, the approach may reduce engine oil consumption. Additionally, the approach may improve engine reliability since engine oil may be exposed to less contaminants.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.